Investigational vaccine for herpes zoster shows promise

An investigational vaccine for herpes zoster provided significant benefit to patients 50 and older, with little difference in efficacy among those in their 50s, 60s, and 70s, according to a phase 3 international trial.

The study results were published April 28 on the New England Journal of Medicine website (NEJM.org).

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More than 15,000 individuals from 18 countries were randomly assigned to receive two doses of HZ/su vaccine, one month apart, or placebo and then followed for a mean of 3.2 years. Half of the study participants received the HZ/su vaccine, an investigational recombinant subunit vaccine that contained varicella-zoster virus and the AS01₈ adjuvant system.

Approximately half of the patients were European (51.2%), and the majority were white (71.8%) and women (61.2%). The mean age of patients at the start of the study was 62.3 years.

Vaccine efficacy

There were 216 confirmed cases of herpes zoster, and six cases occurred in the group that received the investigational vaccine. The rest occurred in those that receive placebo.

“The overall incidence of herpes zoster per 1000 person-years was 0.3 in the HZ/su group and 9.1 in the placebo group, for an overall vaccine efficacy of 97.2%,” the authors noted. In addition, “[t]here was no significant difference in vaccine efficacy among the age groups (range, 96.6% to 97.9%).”

Jeffrey I. Cohen, MD, commented on the trial in the same issue of the New England Journal of Medicine.

“Unlike the live attenuated vaccine, the HZ/su vaccine had an efficacy that did not diminish with increasing age,” Cohen noted. “The efficacy was 96.6% among participants between the ages of 50 and 59 years, 97.4% among those between the ages of 60 and 69 years, and 97.9% among those 70 years of age or older.”

Vaccine safety

Among those who received the HZ/su vaccine, almost 85% experienced a reaction, although most had mild-to-moderate symptoms, the authors reported. Reactions included injection-site pain, redness, and/or swelling and systemic reactions such as myalgia, fatigue, headache, shivering, fever, and gastrointestinal upset.

In the placebo group, fewer patients reported injection-site reactions of pain, redness, and swelling, and systemic reactions.

The safety of the investigational vaccine will continue to be monitored as the trial continues. The trial is known as the Zoster Efficacy Study in Adults 50 Years of Age or Older (ZOE-50).